friedman



Feb. 21, 1956 J. H. FRIEDMAN 2,735,487

NUT PIERCING MACHINE 3 Sheets-Sheet 1 Original Filed June 17, 1949INVENTOR. JOHN H- FRIEDMAN Feb. 21, 1956 J. H. FRIEDMAN 2,735,487

NUT PIERCING MACHINE Original Filed June 17, 1949 3 Sheets-Sheet 2 w, BYN E/CHEY, WATTS E'OGERTONJ M- /VE/V/VY.

ATTOEA/ K5 Feb. 21, 1956 J. H. FRIEDMAN 2,735,487

NUT PIERCING MACHINE Original Filed June 17, 1949 5 Sheets-Sheet 3 32 331 I 24 WM IN VEN TOR.

JOHN H FRIEDMAN R/CHEY WA 77's, EDGEPTONrXM- NENNY United States PatentNUT PIERCING MACHINE John H. Friedman, Titfin, Ohio, assignor to TheNational Machinery Company, Tilfiu, Ohio, a corporation of Ohio Originalapplication June 17, 1949, Serial No. 99,77il. Divided and thisapplication November 25, 1952, Serial N 0. 322,490

8 Claims. (Cl. 164-86) This invention relates to apparatus for piercingblanks and is particularly adapted for use in connection with a coldheader. Reference is made to my co-pending application Serial No. 99,770filed June 17, 1949 now Patent No. 2,645,793 issued July 21, 1953 ofwhich the instant application is a division.

This invention is particularly advantageous where the diameter of thepunched hole is relatively large with regard to the diameter of theblank, in which case difficulty has been encountered due to expansionand permanent set of the blank as a result of a socketing or punchingoperation. It is an object of the invention to pierce blanks, such asnut blanks, while cold, without expanding the blanks and with a minimumof tool wear and breakage. Briefly, this is accomplished by confiningthe blank side wall in a sliding die, bringing a punch or tool againstthe blank, socketing the blank or piercing the blank while confined anduntil a slug has broken loose, and if punching, continuing the punchingmotion to force the slug clear of the blank while simultaneouslyremoving the confinement of the blank side wall. Thus, the slug-severingoperation takes place while the blank is confined; although the blankmay have thin side walls, it will not be stretched or expanded beyondits elastic limit.

In order to prolong tool wear in accordance with the invention, thepunch is withdrawn from the blank after the latter has been carriedclear of the die by the punch, so that the blank is unconfined duringthe stripping operation. In a preferred form of the invention, this isaccomplished by stripping mechanism carried by the header slide whichmay be positioned independently of the punch. The punch is stripped fromthe blank after the latter has been withdrawn clear of the die, whichproduces little or no wear on the punch. The blank can spring slightlyduring stripping which facilitates Withdrawal of the punch, but thisexpansion is not enough to cause a stress that exceeds the elasticlimit, so that the blank returns to its original diameter.

Another object of the invention is to positively and firmly break thepunched slug clear of the nose of the punch after the punch has expelledor pushed the slug into the slug discharge tube. The initial pressurenecessary to sever the slug from the blank is often high enough to causethe slug to adhere firmly to the punch nose so that the slug tends to bewithdrawn with the punch to remain in the blank, instead of beingdeposited in the discharge tube provided for the slugs. In a preferredembodiment of the invention withdrawal of the slug with the punch isconsistently and positively prevented by disposing a tapered shoulderinwardly of the mouth of the slug-receiving passageway, which shoulderis in the path of the slug as the punch projects it into the passageway.Thus, as the punch carries the slug against the shoulder the slug iscammed radially by the shoulder and broken clear of the punch nose.

Another object of the invention is to insure that the blank comes awaywith the punch upon retraction of the slide. This is accomplished byutilizing motion of the punch or tool-carrying means to retract thesliding die that confines the blank after theslug'has been severed fromthe blank. It is also an object to aecomplish this even though blanktransfer fingers may be at and remain at the punching station during thepunching operation. in the preferred arrangement, these objects areattained by providing one or more prongs or ex tensions movable with theheader slide that straddle or clear the transfer fingers and protrudeaxially forwardly. These extensions engage the sliding die or sleevethat surrounds the blank after the slug has been severed from the blankby the punch, and force the die clear of the blank.

The manner in which theseand other objects are accomplished will beapparent from the followingdetailed description of a preferredembodiment of the in' vention.

In the drawings:

Fig. 1 is a simplified section of a cold heading device suitable forcarrying out the invention;

Fig. 2 is a fragmentary elevation showing the tool assembly and aportion of the transfer fingers;

Fig. 3 is a section through the tool and die assembly of the apparatusdisposed just as the punching operation begins;

Fig. 4 is a section showing the apparatus just as the slug is severedfrom the blank;

Fig. 5 shows the slug broken loose from the end of the punch; and,

Fig. 6 shows the header slide retracted partially stripped from theblank.

Although in its broader aspects the invention is not limited to coldheaders, it is particularly adaptable to cold heading machines such asthat shown in the patent to Clouse, 1,856,027, April 26, 1932, and isalso applicable to a nut machine such as disclosed in my pendingapplication, Serial No. 663,569, filed April 19, 1946 now Patent No.2,542,864 issued February 20, 1951. Cold headers adaptable to effectingthe invention include generally a die block, a reciprocable header slideand tools, means to feed stock to the die blank, means to shear offblanks, means to transfer the blanks between stations in the die block,means to advance and retract the header slide to perform work on theblanks, and means to knock out the blanks from the dies into thetransfer means. in Fig. 1 elements of a cold header essential to theinvention are shown, and other elements typical to cold headingapparatus are disclosed, it being understood that except as disclosedherein and claimed the details of the header construction andparticularly the feed, shear, knockout, and transfer mechanism form nopart of the present invention.

As seen in Fig. l, the header frame 1%; has guides 11 for reciprocablymounting a slide S. Slide S is reciproeated by the usual crankshaft 12rotatable in the machine frame which drives the crank or pitrnan 13pivoted to the header slide as at 14. In a preferred embodiment of theinvention, a cam C is mounted on the crankshaft to control the operationof means to strip the punch from the blank. A roller 16 is mounted on acam follower 17 which is pivoted to the frame as at 1% and urged byspring apparatus 19 so that the roller bears against the cam. Thefollower controls a plunger 21, slidably mounted in the header slide.The combined punching and stripping mechanism 22 is mounted in theheader slide, the actual construction thereof ;being somewhat simplifiedin .Fig. 1, It includes the punch or tool P, in independently movablestripping sleeve 24, and an operating plunger 25 for controlling thesleeve:

and the punch I 3 Suitable transfer mechanism such as that disclosed inmy application Serial No. 663,569, filed April 19, 1946, operatetransfer fingers T to transfer blanks from station to station. A dieblock 26 and a punch or die station D are also provided which will bedescribed hereinafter in more detail.

Preferred constructional details of the tool and die assemblies areillustrated in Figs. 2 and 3. As seen in those figures, the header slideS has screwed therein a sleeve 31 which acts as a retainer for a bushing32 having forwardly projecting fingers 33 arranged to pass between thetransfer fingers T. The stripping sleeve 24 surrounds the punch P andslides within the sleeve 32. The punch P is retained in the slide by aninner sleeve 34 and a head 35 on the punch shank, these elements beingforced against the bushing 32 by means of a plug 36 and a clamping wedge33 in accordance with practice well-known in the art. The plunger hasforwardly extending pins 37 which extend through apertures in bushing 34and engage the rearward portion 38 i of the stripping sleeve 24.

The die block 26 incorporates special die or punch station mechanism D.A hardened sleeve member 41 is fastened in the die block and slidablymounts a twopart confining sleeve or die member made up of an outermember 42 and an inner hardened blank-confining sleeve or die 43. Thesliding die assembly is retained in the die block by means of narrowclips 44, and are urged against the clips by an assembly of plungers 46and compression springs 47 fitting within recesses 48 in the sleeve 41.In order to receive the slug punched from the blank, a discharge tube 51is mounted centrally in the die station, and includes a slug-receivingpassageway 53, a tapered shoulder 54 for breaking the slug clear fromthe punch, and a slug-receiving mouth 52 concentric with the punch.

In operation, and in accordance with the usual practice, a blank istransferred by the transfer fingers T and their controlling mechanism toa position. in front of the sliding die member 43. As the header slideadvances, the nose of punch P engages the blank 0 and forces it intosleeve member 43, springs 47 holding the sleeve member in its outennostposition during this operation. As shown in Fig. 1, cam C is contouredso that surface 31 engages the follower 16 during this phase of thecycle and causes the stripping members to move generally forward withthe header slide on the advance stroke. The position of the parts inFig. 3 is such that the punch P has engaged the blank and forced itagainst the shoulder of the discharge tube 51.

Further motion of the header slide causes the punch to pierce and severthe slug 60 from the blank, as seen in Fig. 4. The relationship of partsand the length of fingers 33 is such that just as the slug 6% is severedfrom the blank, fingers 33 are brought into engagement with the slidingdie member 43. It will be noted from Fig. 4 that the blank is confinedduring the slug severing operation, and even though it has relativelythin walls it cannot expand or stretch past its elastic limit. Asadvancing motion of the slide continues, the punch forces the slug 6%through the punched blank 01, and fingers 33 force the sliding die 43clear of the blank. The advancing punch smooths and trues the punchedhole, and, as seen in Figs. 4 and 5, I may form the parts so that theblank is unconfined except at the working zone or nose 61 of the punch.

When the punch approaches the end of its stroke, a corner of slug 60 isforced against the tapered or camming surface 54 of the discharge tube.This radially cams the slug and breaks it clear of the nose of the punchto which it tends to adhere or weld, due to the high pressures resultingfrom punching the confined blank. The punch advances somewhat furtherthan its position in Fig. 5 until the working zone 61 passes through thepunched aperture in the blank. As the header slide re- 4 tracts, thiscauses the punch to remove the blank from the die block.

Initially, the stripping assembly moves back with the slide, because thecam surface 32 of cam C falls away from under the roller 16 as theheader slide retracts. However, a point is reached wherein the surface33 of the cam C is turned under the roller 16, which surface issubstantially equi-distant from the center of rotation of the crankshaft12. This causes the stripping plunger and sleeve apparatus to remainstationary, or substantially so, while the header slide and punch areretracted. As a result, the punch is stripped from the blank which isbrought against the forward nose of the stripping sleeve 24 during thestripping operation. It is noted that the stripping operation occurswhen the blank has cleared the transfer fingers and while it isunconfined so that no permanent expansion may occur, and wear on thetool is greatly reduced. After the blank has been stripped from thepunch the surface 34 of the cam is turned under the follower whichpermits the entire slide, including the stripping assembly to retractwith the header slide. Although I prefer to use a crankshaft-mounted camto operate the stripping assembly as herein disclosed, any means havinga similar mode of operation may be employed to effect independent motionof the punch and stripping sleeve.

Those skilled in the art will recognize that in carrying out theinvention, thin-walled blanks can be pierced or punched without dangerof permanent expansion of the blanks. However, retraction of the tool iseffected while the blanks are unconfined so that tool life is greatlyprolonged. Likewise, there is no possibility of the pierced slug beingretracted with the tool and blank due to the slug-clearing means formedin the slug receiving passageway at the die. Furthermore, the tool isstripped from the blank with the blank well clear of the die andtransfer fingers so that no interference will be encountered.

Although, I have illustrated a preferred form of apparatus for effectingthe objects and advantages of the invention, it will be recognized thatother constructional details and arrangements may be had withoutdeparting from the essence and mode of operation of the invention asdefined by the appended claims.

What is claimed is:

1. In a cold header, a die block and a relatively repicrocable headerslide, a punch on said slide, said die block having formed therein in aslug-receiving bore surrounded by a fixed shoulder for backing up ablank to be punched, a sleeve slidably mounted on said die block andhaving a bore for surrounding and confining the side wall of a blankdisposed against said shoulder, means for positioning said sleeve toconfine the blank before the blank is punched, means to advance saidpunch to punch and sever a slug from the blank while the latter isconfined, means carried by said slide spaced from the outer. peripheryof said blank to engage and progressively move said sleeve as the punchadvances, said sleeve being moved clear of the blank, means to hold saidblank against said shoulder, and means to withdraw said punch means fromthe blank with the sleeve clear of the blank and the side wall thereofunconfined.

2. In a cold header, relatively reciprocable slide and die means, saiddie means having formed therein a slugreceiving bore surrounded by ashoulder for backing up a blank to be punched, a sleeve slidably mountedon said die means and having a bore for surrounding and confining theside wall of a blank disposed against said shoulder, a punch on saidslide for positioning a blank in said sleeve to confine the blank, meansto ad Vance said slide to punch and sever a slug from the blank whilethe latter is confined, means movable with said slide spaced from theouter periphery of said blank to progressively move said sleeve clear ofthe blank simultaneous with movement of said punch, means to withdrawsaid punch means and blank from the die means, and means to strip thepunch from the blank with the sleeve clear of the blank and the sidewall thereof unconfined.

3. Apparatus for piercing blanks comprising relatively reciprocablepunch and blank supporting means, said blank supporting means havingformed therein a slugreceiving bore surrounded by a fixed shoulder forbacking up a blank to be punched, a sleeve slidably mounted on one ofsaid relatively reciprocable means, and having a bore for surroundingand confining the side wall of a blank disposed against said shoulder,means for positioning said sleeve to confine the blank before the blankis punched, projecting means spaced from the outer periphery of saidblank and substantially aligned with said punch means, means to advancesimultaneously said punch means and said projecting means to punch andsever a slug from the blank while the blank is confined by said sleeve,said projecting means contacting said sleeve after the punch meanscontacts the blank to progressively move said sleeve relative to saidblank until said sleeve is clear of the blank, means to withdraw saidpunch means and blank from the sleeve supporting means, and means tostrip the punch from the blank with the sleeve clear of the blank andthe side wall thereof unconfined.

4. Apparatus for piercing blanks comprising relatively reciprocablepunch and blank supporting means, said blank supporting means havingformed therein a slugreceiving bore surrounded by a fixed shoulder forbacking up a blank to be punched, a sleeve slidably mounted on one ofsaid relatively reciprocable means and having a bore for surrounding andconfining the side wall of a blank disposed against said shoulder, meansfor positioning sleeve to confine the blank before the blank is punched,projecting means spaced from the outer periphery of said blank andsubstantially aligned with said punch means, means to advancesimultaneously said punch means and said projecting means to punch andsever a slug from the blank while the blank is confined by said sleeve,said projecting means contacting said sleeve to progressively move saidsleeve relative to said blank until said sleeve is clear of the blank,means in the wall of said slug-receiving bore to break the slug loosefrom the nose of the punch means, means to withdraw said punch means andthe blank from the sleeve supporting means, and means to strip the punchmeans from the blank with the sleeve clear of the blank and the sidewall thereof unconfined.

5. In a cold header, a die block and a relatively reciprocable headerslide, a punch on said slide, said die block having formed therein aslug-receiving bore surrounded by a fixed shoulder for backing up ablank to be punched, a sleeve slidably mounted on said die block andhaving a bore for surrounding and confining the side wall of a blankdisposed against said shoulder, means for positioning a blank in saidsleeve to confine the blank before the blank is punched, projectingmeans spaced from the outer periphery of said blank and substantiallyaligned with said punch means, said means advancing said punch andprojecting means to punch and sever a slug from the blank while theblank is confined, said projecting means contacting said sleeve afterthe punching has started and progressively moving said sleeve relativeto said blank until said sleeve is clear of the blank, and means towithdraw said punch from the blank with the sleeve clear of the blankand the side wall thereof unconfined.

6. In a cold header, a die block and a relatively reciprocable headerslide,

a punch on said slide, said die block having formed therein aslug-receiving bore surrounded by a fixed shoulder for backing up ablank to be punched, a sleeve slidably mounted on said die block andhaving a bore for surrounding and confining the side wall of a blankdisposed against said shoulder, means for positioning a blank in saidsleeve to confine the blank before the blank is punched, projectingmeans spaced from the outer periphery of said blank and substantiallyaligned with said punch means, said means advancing said punch andprojecting means to punch and sever a slug from the blank while theblank is confined, the said projecting means contacting said sleeveafter engagement of the blank by the punch, said projecting meansprogressively moving said sleeve relative to the blank as the punchadvances until said sleeve is clear of the blank after the slug issevered from the blank, and means to withdraw said punch means from theblank with the sleeve clear of the blank and the side wall thereofunconfined.

7. In a cold header, a die block and a relatively reciprocable headerslide, a punch on said slide, said die block having formed therein aslug-receiving bore surrounded by a fixed shoulder for backing up ablank to be punched, a sleeve slidably mounted on said die block andhaving a bore for surrounding and confining the side wall of a blankdisposed against said shoulder, resilient means for urging said sleevetoward said slide, means to position said blank into the sleeve toconfine the blank before the blank is punched, abutment means spacedfrom the outer periphery of said blank and substantially aligned withsaid punch means, said means advancing said punch and abutment means,said punch means severing a slug from the blank while the blank isconfined, said abutment means engaging said sleeve after the punch hasentered the blank, said abutment means progressively moving said sleeveas the punch passes through the blank moving the sleeve clear after thepunch removes the slug from the blank, and means to withdraw said punchmeans from the blank with the sleeve clear of the blank and the sidewall thereof unconfined.

8. In a cold header, a die block and a relatively reciprocable headerslide, a punch on said slide, said die block having formed therein aslug-receiving bore surrounded by a fixed shoulder for backing up ablank to be punched, a sleeve slidably mounted on said die block andhaving a bore for surrounding and confining the side wall of a blankdisposed against said shoulder, means for positioning a blank in saidsleeve to confine the blank before the blank is punched, abutment meansspaced from the outer periphery of said blank and substantially alignedwith said punch means, said punch entering the blank prior to theengagement of said abutment means on said sleeve, said means advancingsaid punch through the blank with said abutment means progressivelymoving the sleeve relative to the blank as the punch advances to severthe slug and to unconfine said blank, means in said slug-receiving boreto engage and break the slug clear of the punch, means to withdraw saidpunch with the blank thereon from the die block, and means to strip theblank from the punch with the sleeve clear of the blank and the sidewall thereof unconfined.

References Cited in the file of this patent UNITED STATES PATENTS840,761 Forbis Jan. 8, 1907 1,900,572 Lyman Mar. 7, 1933 2,547,801Wilcox Apr. 3, 1951

